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10/12/1998 16:09 9165350207 APEX ENVIROTECH PAGE 33 ip q Potential.jifor the Bioremediation of Methyl Tertiary Butyl Ether (MTBE) .....�.r nw-w .......x+...-Y......�wx._. —.,..i.-..,..........r. - - -- -..�u...�_,,.�-. a �..�....�. -"n..n..-..—. ...-. .ti.... •�:- ..:J - Prop er The gasoline oxygenate, methyl tertiary butyl ether (MTBE), presents a serious complication in the remediation and dvsure of properties contaminated with fuel hydrocarbons. Several factors contribute to this;'complexity; 1. MTBE degrades v slowlyunder aerobic conditions. " 2. MTBE is not ed as an anaerobically degradable compound. 3. Unlike BTEX,,l MTBE is highly soluble and does not retard on the aquifer matrix_ The compound in therefore icapable of rapid and pervasive dispersion in groundwater. 4. The toxicity;; nd carcinogenicity of MME have not been established. S. Taste and odor theshoids for MTBE are very low. 6. Although MTBE is extremely volatile, when dissolved in water it is difficult to strip which complicates sparging and pumping options. In the latter case pumped water may have to be treated in bloreactors. .lust when a coherent and manageable protocol for $TEX remediation is being formed by consultants and regulators (Risk Based Con ective"Action - RBCA), the MTHE "wild circ!" has threatened to change the terror of the issue. in the words of one national clean-up manager for a major oil company,,:"We have corse so far in managing thousands of our sites and now I feel like I'm back to square 'one with the MTBE problem." About a year ago, Regenesis began to notice that.in wells containing ORC socks MTBE was !disappearing at an unusually high rate. Data was sparse as MTBE was rarely measured and reported, however ''an intriguing triguin trend was emerging. In some cases the removal rates for MTBE, presumed to be a function of biological degradation, were extremely high. The literature reports f aerobic degradation l�rate constants in a range of .0231 to .0038 (half-life of 30 to 182 days). In the Regenesis data,;from 11 wells across three diverse oil company sites (CA, Ml and N1), degradation rate constants were in a range of _1447 to .0112 (half-life of 5 to 61 days):The i question then became - "What Is.the role of ORC in this process?" Figures 1 to 3 present examples of STEX and MT$E degradation in a single representative well for each of the three sites referenced above. Each example also reflects a low, moderate and high background level of"HTEX. We believe that the presence of background hydrocarbons can interfere with the metabolism"of MT$E by cornpatent microorganisms. Thus, the documented impact of ORC ` on BTEX is an important factor in MTBE bioremediation. i This important hypothesis evolved as a result of sharing the data with other"researchers in the E